Variable-voltage transformer.



A. SIMON.

VARIABLE VOLTAGE TRANSFOBMER.

APPLICATION man 1u|.Y 3,1915.

1,227,844. Patented May 29,1917.

5E E 51 .IIIII gmail. l

AUNITED sTATEs PATENT oEEIcE.

ARTHUR SIMON, OI MILWAUKEE, WISCONSIN, ASSIGNOB TO THE CUTLEBf-HAMMEBMFG CO., OF MILWAUKEE, WISCONSIN, CORPORATION OF WISCONSIN.

VARIABLE-VOLTAGE TRANSFORMER.

Specification of Letters Patent.

Patented May 29, 1917.

Appncationnled :my a, 191s. serial No. 37,998.

n To all inkom t may concern 4 will be apparent thatntransformersembodying various features of the invention may beadvantageouslyemployed in other relations.

One of the objects of the invention is to provide an inclos'edtransformer of simple, compact and durable construction.

A further object is to provide an adjustable transformer Capable ofvoltage regulation. between predetermined limits in very minute degrees.

The accompanying drawin' illustrates one embodiment of the invention andthe same will now be described, it being understood that`the inventionAis susceptible of various modifications falling within the spirit andscope of the appended claims.

Figure 1 is a top view of the transformer with a portion thereof brokenaway.

Fig. 2 is a front view thereof.

Fig. 3 is a sectional view taken along the lines 3--3 of Fig. 1.

Fig. 4' is a front view of the transformer with the cover removed, and

Fig. 5-is a diagrammatic view showing the transformer connectedin a lampcircuit.

Briefly described, the transformer includes coils 1 and 2 mounted on acore 3 and provided with an adjustable armature 4, all

. of the aforesaid elements being mounted in l j side plates 11 fastenedtogether by rivets 12 and secured by screws 13 to lugs 14 projectingupwardly from the bottom of the casing section 5. It is to be here notedthat the central leg 8 of the core 3 is shorter and of smaller crosssectional area than the legs 7 and 9, functioning in a manner which willbe hereinafter set forth.

The armature 4 comprises a rectangular bar of suicient length to extendacross the legs 7 and 9 of the core 3 and is preferably built up' oflaminations 16 confined between side plates 17 and fastened together byrivets 18. The armature 4 is slidably mounted between a shoulder 19within casing section 6 and an elongated lug 2O projecting upwardly fromthe bottom of casing section 5 and is provided with an adjusting screw21. The screw 21V as best illustrated in Fig. 1, is connected to thearmature 4 by a threaded nut 22 formed by projecting the side plates 17of the armature 4 beyond the laminations 16 vand bending the same atright angles toward each other -in an overlapping` relation.. The screw21 passes through an opening 23 in the endv wall of casing section 6 andis secured against endwise movement by a knob 24 on the outside of saidsection 6 and a shoulder 25 on the inside thereof. Rotation of the knob24 rotates the screw 21 which through its screw threaded engagement withthe nut 22 produces endwise adjustmenty of the armature 4 for a purposewhich will be hereinafter set forth. In practice there is considerabletendency' for the armature 4 to vibrate and in order `to prevent i unduevibration the same is provided with a leaf spring 26 having reflexedends 26 adapted to bear against the side wall of casing member 6 andresiliently hold the armature 4 in engagement withthe oo re 3. A

Before proceeding further the function and operation of the transformerwill be described in connection with Fig. 5. As before stated thetransformer is particularly adapted for use with projecting arc lampsand in Fig. 5 a lamp is diagrammatically illustrated as provided withcarbons 27 and 28 connected by conductors 29 and 30 to the terminals ofthe coil 2. The coil 1 is Vconnected across the linesL and L andfunctions as the primary coil of the transformer to generate lines` offorce which passing through the coil 2; or secondary coll of thetransformer, excites the latter. However, due to the Efshapedconstruction of the core -j 3 two magnetic circ-uits are provided, forthe lines of force generated by the primary coil 1, one extendingthrough the leg 9 and the other in shunt thereto through the leg 8. Itwill be understood by those skilled in the art that if the magneticreluctance of the circuit passing through the leg 9 is varied the ratiobetween the number of lines of force passing through this leg and thosepassing in shunt thereto through the leg 8, will vary and produce avariation in the 1nduced voltage of the coil 2. The reluctance of themagnetic circuit passing through the leg 9 is varied by the armature 4.which -is adjusted endwise to vary the contact surface between the sameand the end of the leg 9.v An increase in contact area between theseparts willefect a decrease in the magnetic reluctance of the circuittherethrough and a decrease in contact area will increase` thereluctance thereof. It is therefore obvious that movement of thearmature 4 toward its extreme right hand position as shown in full linesin Fig. 5 increases the number of lines of force passing through the leg9 thereby effecting an increase in the inv duced voltage of the coil 2while movement towar the left hand position as shown in dotted linesAproduces. an opposite effect.

It is to be here noted that the voltage limits between which thetransformer isA adapted for regulation is'ldetermined by the relativevle .reluctances of the magnetic circuits passing through the legs 8 and9. In the transformer illustrated .it is desired when the armature 4is.in its extreme right hand position, `that the reluctance of themagnetic circuit passing through the leg 8 be high in comparison to thatof the circuit passing through the leg 9. The magnetic reluctance of thecircuit passing through the-leg 8 is made relatively high by making itshorter than the legs 7 and'9, to provide an air .gap between the sameand armature 4v and also by making the cross sectional area thereofrelatively small in comparison to .9. Here it should be noted that byslightly adjusting the armature 4 endwise the secondary voltage can bleregulated in very minute degrees and that the screw 21, due to itsthreaded engagement with the armature 4 enables a very line adjustmentvthereof.

Again referring to the mechanical struc` ture it will be observed fromFigs. 1 and 2 that the casing sections '5 and 6 each comprise arectangular box-like member having'j Ventilating openings 31 therein.The casing sections 5 and 6 are secured together by screws 32 passingthrough the front wall of the casing .section 6 andengaging tapped lugs33 f von the inside of the casing Y casing section, 5 is provided onopposi e section 5. T e

ends with openings containin insulating bushings 34 for the reception oconductors and is also provided with a projection 35 for' limitingadjustment of the armature 4 toward the left.

It will of course be understood that the 7 specific transformer abovedescribed is to be considered merely as illustrative of the presentinvention and that the same is susceptible of various modificationsfalling Within the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent is l. In avariable voltage transformer, in

combination, a primary coil, a secondary,8

coil, an E-shaped core therefor, said Lcoils being separately mounted ontwo legs of said core, the third leg of said core providing a magneticshunt for said primary coil and an armature bridging all of said A legs,said armature being adjustable to in.- crease and decrease thereluctance of the magnetic circuit passing through the leg of saidsecondarycoil to respectively decrease and increase the induced yvoltageof said secondary coil. y

2. In a variable voltage transformer, in combination, a primary coil, asecondary coil, an E-shaped core therefor, vsaid coils being .separatelymountedon the end legs of core, the middle leg of said core providing amagnetic shunt for said primary coil and an armature bridg'in all ofsaid legs, said armature being adjustable to increase and decrease thereluctance of I the magnetic circuit passing throughl the leg Aof saidsecondary coil to' respectively decrease and increase the inducedvoltage of said secondary coil.

-3. In a variable voltage transformer, in

combination, a primary coil, a secondary coil, an E-shaped coretherefor, said coils being separately mounted on .two legs ofv said coreand the third leg of said.v core providing a magnetic shunt for saidpri-110' mary coil and being of relatively higher reluctance than theleg of said secondary coil and an armatue bridging all of'said legs,said armature being adjustable to increase and decrease thereluctancevof the 1(15 magnetic circuit passing through the leg of saidsecondary coil to respectively decrease and-'increase the inducedvoltage o said secondary coil.

-4. I n a `variable voltage transformer, .in

combination, a primary coil, a secondary coil, an E-shaped coretherefor, said coils 1 being separatelmounted on the end-legs of saidcore, te middle leg of said core 'providin marycoll and bein ofrelatively hi 'her reluctance than the eg of said 'secon ary coil andanarmature common to the three legs of said'core, said armature being1011-V gitudinally adjustable "to increase and de- 1'30 a magneticshuntfor said pri- 125 I crease the reluctance of the magnetic circreasethe induced voltage of said second-` ary coil.

5. In avariable voltage transfoii'mer, in combination, a primary coil, asecondary coil a substantially E-shaped core therefor, said coils beingmounted on two legs of said core and the third leg `being of restrictedcross sectional area and length relative to said former legs and alongitudinally adjustable armature common to said legs.

In a variablevoltagc transformer, the combination with a two-partinclosing casing, of an E-shaped core carried within one part of saidcasing, coils carried by said core, an adjustable armature associatedwith said core, said armature being slidably supported on opposite sidesbetween the parts of said casing and means operable from the outside ofsaid casing for adjusting said armature.

7. In a variable voltage transformer, the combination with a two-partinclosing casing, of a laminated core mounted within 'said casing, coilscarried by said core, an

adjustable armature associated with said core, said armature beingslidably supported on opposite sides between the two parts of saidcasing, and means operable from the outside of said casing for adjustingsaid armature.-

8. In a variable voltage transformer, the combination with an inclosingcasing comprising two relativelyl inverted box-like sections, of a coremounted within said casing tions, of an E-shaped core carried within,v

said casing and secured to one of the sections thereof, a coil mountedon each of the end legs of said core, an armature cooperating with theend legs of said core and adjustable relatively thereto, said armaturebeing slidably mounted between projecting portions on each of thesections of said casing and a screw operable from the outside of saidcasing for adjusting said armature.

l0. In a variable voltage transformer, the combination with an inclosingcasing comprising two relatively inverted `box-like sections, of alaminated E-shaped core mounted within said casing and secured to one ofthe sections thereof, a coil carried on each of the end legs of saidcore, a laminated armature bridging the extremities of the end legs ofsaid core, said armature being slidably supported between projectingportions on each of the sections of said casing and a screw operablefrom the outside of said casing for longitudinally adjusting saidarmature.

11. In a variable voltage transformer, the combination with an inclosingcasingcomprising two rectangular relatively inverted box-like sectionsprovided with a plurality of ventilating openings, a fiat E-shapedlaminated core mounted within said casing and secured to one of thesections thereof,

a coil carried on each of the end legs of said core, a laminatedarmature bridging the extremities of the end legs of said core, saidmember being slidably supported between projecting portions on each ofthe sections of said casing, a rotatable screw having an operating knobon the outside of said casing for longitudinally adjusting said armatureand resilient means secured to said z armature and interposed betweenthe same and the inside wall of said casing for yieldingly holding saidarmature in engagement with said core.

In witness whereof, I have hereunto subscribed my name.

ARTHUR SIMON.

